Zoom in/out on panel -- efficient way?

Question

I need a panel to display an image, I want to be able to zoom in/out on that image, and have the panel resized (which would need to adjust the image being shown so that it fills the panel)....below is sort of what I was thinking...but is there a more efficient way?
public void paint(Graphics g) {
     at =  new AffineTransform();
     int w = getParent().getWidth();
     int h = getParent().getHeight();
     int picW = pic.getWidth();
     int picH = pic.getHeight();
     double newW = ((double) w / (double) picW);
     double newH = ((double) h / (double) picH);
     at.scale(newW, newH);
     ((Graphics2D) g).drawImage(myImage, at, null);
}Thanks

Answer 1

1) Don't extent paint(), extend paintComponent()
2) Keep a local copy of the image in your class. Use Image.getScaledImage()
whenever the user changes the zoom level to modify your local copy. Have
paintComponent reference the local copy.
This way, you're only performing an expensive computation when the zoom
actually changes, which is relatively infrequent, rather than every time you
have to repaint, which is relatively often.